The development of sex role stereotypes-specifically, beliefs about the activities and possessions differentially associated with males and females in our society-will be examined in children between the ages of two and three years. The content of these sex role stereotypes, their onset and developmental course, the relationship of sex role stereotypes to sex-typed behavior, gender knowledge of others, and gender identity, and specific environmental factors that development of these processes will be investigated. Three studies have been designed. Study 1 will examine the development of sex role stereotypes, sex-typed toy preferences, gender knowledge and gender identity cross-sectionally in children 2, 2 1/2, and 3 years of age. Differences as a function of maternal employment will be explored by considering the effects of specific hypothesized process variables--stereotypy of division of household labor, maternal androgeny, maternal attitudes toward women and child rearing practices regarding sex stereotypic differences in children. In Study 2, the effects on sex role development of being reared in a single parent family will be investigated in a similar fashion. Finally, in Study 3, the development of sex role stereotypes, sex-typed toy preference, gender knowledge, and gender identity will be examined longitudinally. Specific theoretical predictions regarding the developmental sequence of the sex role process will be tested using cross-lagged panel correlations. The results of these studies have important theoretical implications for our understanding of sex role socialization, and of the relationship between early social and cognitive development. In addition, the results have practical implications for understanding the origins of sex role stereotypes and the effects of alternative family styles.